Cable winding mechanism with reduced friction

ABSTRACT

A cable winding mechanism with reduced friction includes a cable, a case, a reel disc, a spring device, a roller and a friction-reducing member. The case includes a first case element and a second case element, wherein a cable locking structure is formed in an inner surface of the second case element. The reel disc has a confining groove. The roller is movable along the confining groove of the reel disc. When a pulling operation of the cable causes the roller to move in the cable locking structure of the second case element, a desired length of the cable is pulled out and locked. When the roller is detached from the cable locking structure, the cable pulled outside the case is rewound on the reel disc. The friction-reducing member is disposed on the reel disc for reducing friction during the process of pulling out or rewinding the cable.

FIELD OF THE INVENTION

The present invention relates to a cable winding mechanism, and more particularly to a cable winding mechanism with reduced friction.

BACKGROUND OF THE INVENTION

With increasing development of high technology industries, electronics devices such as notebook computers, phones, digital cameras and the like are widely used in our daily lives. Conventionally, these electronic devices are communicated with the power source via the linkage of power cables or communicated with other electronic devices via the linkage of signal cables. In other words, power cables and signal cables are utilized as transmission media for transmitting power and signals, respectively. Since these cables have several meters in length, it is critical to gather these cables for storage. Recently, many cable winding mechanisms have been proposed to wind cables for storage.

For example, a USB cable adapter with a cable winding mechanism is disclosed in U.S. Pat. No. 6,733,328 and the contents thereof are hereby incorporated by reference. FIGS. 1A and 1B are respectively schematic assembled and exploded views illustrating the USB cable adapter disclosed in U.S. Pat. No. 6,733,328. The USB cable adapter of FIGS. 1A and 1B principally includes a USB connector 10, a signal connector 11 and a cable winding mechanism 12. The USB connector 10 is coupled to an electronic device having a USB interface (e.g. a computer host). The signal connector 11 is coupled to an electronic device having a signal connecting interface (e.g. a digital camera or a charger).

The cable winding mechanism 12 is interconnected between the USB connector 10 and the signal connector 11. The cable winding mechanism 12 includes a case 121, a reel disc 122, a roller 123, a spiral spring 124 and a cable 125.

The case 121 comprises a first case element 1211 and a second case element 1212. A spool 1213 is extended from an inner surface of the first case element 1211 for securing the reel disc 122 thereon. A longitudinal gap 1214 is cut through the spool 1213 for anchoring the spiral spring 124 onto the spool 1213 such that the spiral spring 124 is fixed between the first case element 1211 and the reel disc 122. In addition, a confining groove 1215 is formed in the an inner surface of the second case element 1212 such that the roller 123 is moveable along the confining groove 1215 after the first case element 1211 and the second case element 1212 are combined together.

The reel disc 122 is rotatable for winding the cable 125. A channel 1221, a guiding groove 1222 and a curved trough 1223 are formed in the outer surface of the reel disc 122. The guiding groove 1222 is disposed adjacent to the curved trough 1223 for anchoring the roller 123. The curved trough 1223 is disposed adjacent to the guiding groove 1222 and in communication with one end of the channel 1221 for restraining the movable range of the roller 123.

One end of the cable 125 is coupled to the USB connector 10, the other end thereof is coupled to the signal connector 11, and the intermediate portion thereof is wound inside of the reel disc 122. In response to pulling forces exerted on the USB connector 10 and the signal connector 11, the reel disc 122 and the spiral spring 124 are rotated counterclockwise such that the roller 123 moves in the channel 1221 toward the curved trough 1223. At the same time, the spiral spring 124 is being deformed. A sudden release of the pulling forces will cause the roller 123 to move in the guiding groove 1222 such that the reel disc 122 stops rotating and the cable 125 is locked. In other words, a user can lock the cable 125 by releasing the cable 125 after a desired length of the cable 125 has been pulled from the reel disc 122. Again, a continuous pulling operation of the cable 125 from the locked position will cause the roller 123 to move from the guiding groove 1222 to the channel 1221. Eventually, a release of the cable 125 causes the roller 123 to move in the guiding groove 1222 again for locking.

For rewinding the cable 125, the use may slightly pull the cable 125 to cause the roller 123 to clear from the guiding groove 1222. Next, a release of the cable 125 causes the compressed spiral spring 124 to release its stored energy to rotate the reel disc 122 clockwise. As a consequence, the cable 125 is completely rewound on the reel disc 122 if no stopping action is taken.

Although the cable winding mechanism 12 can wind the cable 125 for storage, there are still some drawbacks. For example, during the process of pulling or rewinding the cable 125, considerable friction is readily generated between the adjacent layers of the cable 125 wound around the reel disc 122, between the reel disc 122 and the case 121, and/or between the reel disc 122 and the spool 1213. Due to the friction, these components are abraded. Under this circumstance, the utility of the cable winding mechanism 12 is reduced and the touch feel of operating the cable winding mechanism 12 is impaired. On the other hand, the adjacent layers of the cable 125 wound around the reel disc 122 may be entangled with each other, so that the use life of the cable winding mechanism 12 is reduced.

To overcome the disadvantages of the prior art described above, the present invention provides a cable winding mechanism with reduced friction.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a cable winding mechanism for reducing the friction generated between the adjacent layers of the cable wound around the reel disc, between the reel disc and the case, and/or between the reel disc and the spool during the process of pulling or rewinding the cable. Due to the reduced friction, the pulling force required to pull out the cable is decreased and the problem of causing abrasion is minimized.

Another object of present invention provides a power cable winding mechanism with reduced friction, so that the utility and the touch feel of operating the cable winding mechanism are enhanced and the problem of causing the entangled cable is avoided.

In accordance with an aspect of the present invention, there is provided a cable winding mechanism with reduced friction. The cable winding mechanism includes a cable, a case, a reel disc, a spring device, a roller and a friction-reducing member. The case includes a first case element and a second case element, wherein a cable locking structure is formed in an inner surface of the second case element. The reel disc is disposed between the first case element and the second case element for winding the cable thereon, wherein the reel disc has a confining groove. The spring device is arranged between the first case element and the reel disc. The roller is movable along the confining groove of the reel disc. When a pulling operation of the cable causes the roller to move in the cable locking structure of the second case element, a desired length of the cable is pulled out and locked. When the roller is detached from the cable locking structure, the cable pulled outside the case is rewound on the reel disc. The friction-reducing member is disposed on the reel disc for reducing friction during the process of pulling out or rewinding the cable.

The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic assembled view of a conventional USB signal cable adapter;

FIG. 1B is a schematic exploded view of the USB signal cable adapter shown in FIG. 1A;

FIG. 2A is a schematic assembled view of a cable winding mechanism with reduced friction according to a preferred embodiment of the present invention;

FIG. 2B is a schematic exploded view of the cable winding mechanism shown in FIG. 2A;

FIG. 2C is a backside view illustrating the relation between the reel disc and the cable shown in the cable winding mechanism of FIG. 2B;

FIG. 2D is a schematic view illustrating the cable wound around the reel disc; and

FIGS. 3A, 3B, 3C and 3D are schematic views illustrating operations of the cable winding mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.

FIGS. 2A and 2B are respectively schematic assembled and exploded views illustrating a cable winding mechanism with reduced friction according to a preferred embodiment of the present invention. The cable winding mechanism 2 can be a power cable winding mechanism and principally includes a case 20, a cable 21, a spring device 22, a reel disc 23, a roller 24 and friction-reducing member 25.

An example of the cable 21 includes but is not limited to a DC power cable. The spring device 22 is for example a spiral spring. The cable 21 can be stored within the case 20. Both ends of the cable 21 have respective connectors 211, which are coupled to respective electronic devices having the identical connecting interface.

The case 20 comprises a first case element 201 and a second case element 202. A spool 2011 is extended from an inner surface of the first case element 201 for securing the spring device 22 and the reel disc 23 thereon. A coupling part 2016 is disposed on the spool 2011. The diameter of the coupling part 2016 is smaller than that of the spool 2011. A longitudinal gap 2012 is cut through the spool 2011. In addition, a cable locking structure 2021, a channel 2022 and a curved trough 2023 are formed in an inner surface of the second case element 202. The cable locking structure 2021 is disposed adjacent to the channel 2022 for anchoring the roller 24. The curved trough 2023 is disposed adjacent to the cable locking structure 2021 and in communication with one end of the channel 2021 for restraining the movable range of the roller 24.

In some embodiment, the first case element 201 and the second case element 202 are combined together via an ultrasonic welding technology. Alternatively, the first case element 201 and the second case element 202 are combined together by screwing or fastening means. Moreover, two first protrusion pieces 2013 are formed on opposite sides of the first case element 201. In addition, two second protrusion pieces 2024 are formed on corresponding locations of the inner surfaces of the second case element 202. When the first case element 201 and the second case element 202 are combined together, the first protrusion pieces 2013 of the first case element 201 are engaged with respective second protrusion pieces 2024 of the second case element 202. Under this circumstance, the first protrusion pieces 2013 and the second protrusion pieces 2024 are partially sustained against the connectors 211 such that the connectors 211 at both ends of the cable 21 are partially accommodated within the case 20. The assembled structure of the cable winding mechanism 2 can be seen in FIG. 2A.

In some embodiments, two first concave portions 2014 are formed on opposite sidewalls of the first case element 201 and adjacent to the first protrusion pieces 2013. In addition, two second concave portions 2025 are formed on corresponding locations of the sidewalls of the second case element 202 and adjacent to the second protrusion pieces 2024. When the first case element 201 and the second case element 202 are combined together, two depressions 203 (as shown in FIG. 2A) are defined by the concave portions 2014 and 2025. By inserting a finger into the depressions 203, the user may easily pull out the connectors 211 at both ends of the cable 21 to detach from the case 20.

For adjusting degree of tightness of pulling out or rewinding the cable 21, the cable winding mechanism 2 further includes a tightness adjusting element 26 (e.g. a screw). A thread aperture 2015 is formed in the center of the longitudinal gap 2012 of the spool 2011. Corresponding to the thread aperture 2015, a hole 2026 is formed in the second case element 202. After the first case element 201 and the second case element 202 are combined together via an ultrasonic welding technology, the tightness adjusting element 26 is penetrated through the hole 2026 of the second case element 202 and then screwed in the thread aperture 2015 of the spool 2011 of the first case element 201. Depending on the desired degree of tightness of pulling out or rewinding the cable 21, the degree of tightness of fastening the tightness adjusting element 26 may be varied as required.

FIG. 2C is a backside view illustrating the relation between the reel disc and the cable shown in the cable winding mechanism of FIG. 2B. Please refer to FIGS. 2A, 2B and 2C. The reel disc 23 is arranged between the first case element 201 and the second case element 202 for winding the cable 21 thereon. The reel disc 23 has a receptacle for accommodating the spring device 22 therein. A confining groove 232 is formed in the outer surface of the top plate 231 of the reel disc 23 such that the roller 24 is moveable along the confining groove 232 after the first case element 201 and the second case element 202 are combined together.

Please refer to FIGS. 2B and 2C again. The reel disc 23 further includes a retaining opening 233, a first cable groove 234, a second cable groove 235, a notch 236 and several fastening recesses 237. The retaining opening 233 is formed in a center of the reel disc 23 and adjacent to the confining groove 232. The reel disc 23 is sheathed around the spool 2011 of the first case element 201 through the retaining opening 233 such that the reel disc 23 is fixed on the first case element 201. The fastening recesses 237 are formed in a sidewall 238 of the reel disc 23. The first cable groove 234 and the second cable groove 235 are formed at opposite sides of the sidewall 238 of the reel disc 23. A portion of the cable 21 is supported in the first cable groove 234 and the second cable groove 235 and received within the receptacle of the reel disc 23. The first cable groove 234 is extended from the bottom periphery 2381 of the reel disc 23 to a half thickness of the reel disc 23 (as is shown in FIG. 3C). The width of the first cable groove 234 is substantially equal to the thickness of the cable 21 such that the cable 21 is sustained against the first cable groove 234. The second cable groove 235 is extended from the bottom periphery 2381 to the top plate 231 of the reel disc 23. The second cable groove 235 is tapered from the top plate 231 to the bottom periphery 2381. As a consequence, the cable 21 may be positioned in the second cable groove 235 adjacent to the top plate 231 of the reel disc 23. The cable 21 extended outside the reel disc 23 through the first cable groove 234 and the second cable groove 235 is wound around the upper portion and the lower portion of the reel disc 23 to respectively define a first winding cable set 21 a and a second winding cable set 21 b, as can be seen in FIG. 2D. The notch 236 is formed in the sidewall 238 of the reel disc 23 and arranged between the first cable groove 234 and the second cable groove 235.

In some embodiments, the reel disc 23 further includes a clamping part 239 within the receptacle of the reel disc 23. One side of the clamping part 239 is connected to the top plate 231. The clamping part 239 is arranged in the vicinity of the sidewall 238 of the reel disc 23 such that the cable 21 inside the reel disc 23 is clamped between the clamping part 239 and the sidewall 238 of the reel disc 23.

Please refer to FIGS. 2B, 2C and 2D. The spring device 22 is accommodated within the receptacle of the reel disc 23 to provide a retractive force required for rewinding the cable 21. The spring device 22 has an anchoring end 221 and a hooking end 222. The anchoring end 221 is formed as a straight piece inserted into the longitudinal gap 2012 of the spool 2011 for anchoring the spring device 22 onto the spool 2011. The hooking end 222 is engaged with the sidewall 238 between the notch 236 and the first cable groove 234 or between the notch 236 and the second cable groove 235. By means of the anchoring end 221 and the hooking end 222, the spring device 22 is fixed between the first case element 201 and the reel disc 23.

The roller 24 is movable along the confining groove 232 of the reel disc 23. After the first case element 201 and the second case element 202 are combined together, the roller 24 is confined between the confining groove 232 of the reel disc 23 and the channel 2022 of the second case element 202.

The friction-reducing member 25 is disposed within the case 20 and arranged on the reel disc 23. The friction-reducing member 25 is used to reduce the friction force generated when the cable 21 is pulled out or rewound. The friction-reducing member 25 is one selected from a group consisting of a partition plate 251, multiple salients 252, a ring-shaped article 253 and the combination thereof.

Take the partition plate 251 as the friction-reducing member 25 for example. The partition plate 251 has a hollow portion in the center thereof and sheathed around the reel disc 23 such that the partition plate 251 is arranged between the first winding cable set 21 a and the second winding cable set 21 b. As shown in FIG. 2D, since the first winding cable set 21 a is separated from the second winding cable set 21 b by the partition plate 251, the first winding cable set 21 a and the second winding cable set 21 b will not rub against each other during the process of pulling out or rewinding the cable 21. Under this circumstance, the first winding cable set 21 a and the second winding cable set 21 b will be no longer entangled with each other, so that the use life of the cable winding mechanism 2 is increased. Moreover, the partition plate 251 has several protrusion pieces 2511 corresponding to the fastening recesses 237 of the reel disc 23. After the protrusion pieces 2511 are engaged with the fastening recesses 237, the partition plate 251 is fixed onto the reel disc 23.

Take the salients 252 as the friction-reducing member 25 for example. The salients 252 are arranged on the top plate 231 of the reel disc 23. Examples of the salients 252 include but are limited to spherical beads. After the first case element 201 and the second case element 202 are combined together, the inner surface of the second case element 202 is contacted with the salients 252. Since the contact area between the top plate 231 of the reel disc 23 and the second case element 202 is reduced, the friction force generated when the reel disc 23 is rotated will be decreased. The number of the salients 252 may be varied according to the practical requirement. It is preferred that the number of the salients 252 is three. For example, only one salient 252 is sufficient to offer point contact between the top plate 231 of the reel disc 23 and the second case element 202. Alternatively, some salients 252 may be integrated into a raised block. By reducing the friction force, the user may smoothly pull out or rewinding the cable 21. It is noted that, however, those skilled in the art will readily observe that numerous modifications and alterations may be made while retaining the teachings of the invention. For example, the salients 252 may be arranged on the bottom periphery of the sidewall 238 of the reel disc 23 in order to reduce the contact area between the reel disc 23 and the first case element 201. As a consequence, the friction force generated when the reel disc 23 is rotated will be decreased.

Take the ring-shaped article 253 as the friction-reducing member 25 for example. The ring-shaped article 253 is a hollow cylinder such as a metallic ring. After the reel disc 23 is sheathed around the spool 2011 of the first case element 201 through the retaining opening 233, the ring-shaped article 253 is sheathed around the coupling part 2016 and embedded within and contacted with the retaining opening 233. Since the ring-shaped article 253 made of metallic material has a smooth surface, the friction force generated when the reel disc 23 is rotated will be decreased. The ring-shaped article 253 may be made of other material as long as the friction force generated upon rotation of the reel disc 23 is reduced. Alternatively, the ring-shaped article 253 may have been previously formed or embedded within the retaining opening 233 of the reel disc 23.

The friction-reducing member 25 of the cable winding mechanism 2 may be a combination of two or more of the partition plate 251, the salients 252 and the ring-shaped article 253.

Hereinafter, a process of assembling the cable winding mechanism 2 will be described in more details with reference to FIGS. 2A, 2B, 2C and 2D.

First of all, the hooking end 222 of the spring device 22 is engaged with the sidewall 238 between the notch 236 and the first cable groove 234 of the reel disc 23 or between the notch 236 and the second cable groove 235 of reel disc 23, so that the spring device 22 is fixed in the receptacle of the reel disc 23. Next, the middle portion of the cable 21 is positioned in the second cable groove 235 adjacent to the top plate 231 of the reel disc 23. Next, a portion of the cable 21 is clamped between the clamping part 239 and the sidewall 238 of the reel disc 23, so that the cable 21 is fixed in the receptacle of the reel disc 23. Next, the protrusion pieces 2511 of the partition plate 251 are engaged with the fastening recesses 237 of the reel disc 23, so that the partition plate 251 is sheathed around the middle portion of the reel disc 23. Next, the cable 21 is extended outside the reel disc 23 through the first cable groove 234. Next, the cable 21 outside the reel disc 23 is wound around the upper portion and the lower portion of the reel disc 23 to respectively define a first winding cable set 21 a and a second winding cable set 21 b.

Next, the anchoring end 221 is inserted into the longitudinal gap 2012 of the spool 2011 for anchoring the spring device 22 onto the spool 2011. After the reel disc 23 is sheathed around the spool 2011 of the first case element 201, the ring-shaped article 253 is sheathed around the coupling part 2016 and embedded within the retaining opening 233. Meanwhile, the reel disc 23, the spring device 22 and the ring-shaped article 253 are fixed on the spool 2011 of the first case element 201. Next, the roller 24 is placed into the confining groove 232 of the reel disc 23. Next, the second case element 202 is placed on the first case element 201 and thus the roller 24 is received in the channel 2022 of the second case element 202. By using an ultrasonic welding technology, the first case element 201 and the second case element 202 are coupled with each other. After the tightness adjusting element 26 is penetrated through the hole 2026 of the second case element 202 and then screwed in the thread aperture 2015 of the spool 2011 of the first case element 201, a resulting structure of the cable winding mechanism 2 is assembled, as can be seen in FIG. 2A.

Hereinafter, the operations of the cable winding mechanism 2 will be illustrated with reference to FIGS. 3A, 3B, 3C and 3D. As shown in FIG 3A, in response to pulling forces exerted on the two connectors 211, the reel disc 23 and the spring device 22 are rotated counterclockwise such that the roller 24 moves in the channel 2022 toward the curved trough 2023. At the same time, the spring device 22 is being deformed. A sudden release of the pulling forces will cause the roller 24 to move in the cable locking structure 2021 such that the reel disc 23 stops rotating and the cable 21 is locked, as is shown in FIG. 3B. In other words, a user can lock the cable 21 by releasing the cable 21 after a desired length of the cable 21 has been pulled from the reel disc 23. Again, as is shown in FIG. 3C, a continuous pulling operation of the cable 21 from the locked position will cause the roller 24 to move from the cable locking structure 2021 to the channel 2022.

For rewinding the cable 21, the use may slightly pull the cable 21 to cause the roller 24 to clear from the cable locking structure 2021. Next, a release of the cable 21 causes the compressed spring device 22 to release its stored energy to rotate the reel disc 23 clockwise, as can be seen in FIG. 3D. As a consequence, the cable 21 is completely rewound on the reel disc 23 if no stopping action is taken.

From the above description, by mounting the friction-reducing member 25 (e.g. a partition plate, multiple salients, a ring-shaped article or the combination thereof) on the reel disc, the friction between the reel disc and the case and/or between the reel disc and the spool upon rotation of the reel disc is reduced. Due to the reduced friction, the pulling force required to pull out the cable is decreased and the problem of causing abrasion is minimized. Furthermore, the utility and the touch feel of operating the cable winding mechanism are enhanced. Since the first winding cable set and the second winding cable set are separated from each other by the partition plate, the problem of causing the entangled cable is avoided and thus the use life of the cable winding mechanism is extended.

While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures. 

1. A cable winding mechanism with reduced friction, said cable winding mechanism comprising: a cable; a case including a first case element and a second case element, wherein a cable locking structure is formed in an inner surface of said second case element; a reel disc disposed between said first case element and said second case element for winding said cable thereon, wherein said reel disc has a confining groove; a spring device arranged between said first case element and said reel disc; a roller movable along said confining groove of said reel disc, wherein a desired length of said cable is pulled out and locked when a pulling operation of said cable causes said roller to move in said cable locking structure of said second case element, and said cable pulled outside said case is rewound on said reel disc when said roller is detached from said cable locking structure; and a friction-reducing member disposed on said reel disc for reducing friction during the process of pulling out or rewinding said cable.
 2. The cable winding mechanism according to claim 1 wherein said first case element and said second case element are combined together via an ultrasonic welding technology.
 3. The cable winding mechanism according to claim 1 further comprising two connectors respectively coupled to both ends of said cable.
 4. The cable winding mechanism according to claim 3 further comprising: multiple first protrusion pieces formed on opposite sides of said first case element; and multiple second protrusion pieces formed on corresponding locations of the inner surfaces of the second case element, wherein said first protrusion pieces and said second protrusion pieces are partially sustained against said connectors such that said connectors at both ends of said cable are partially accommodated within said case.
 5. The cable winding mechanism according to claim 1 further comprising: multiple first concave portions formed on opposite sidewall of said first case element; and multiple second concave portions formed on opposite sidewall of said second case element corresponding to said first concave portions, wherein said first concave portions and said second concave portions cooperatively define multiple depressions when said first case element and said second case element are combined together.
 6. The cable winding mechanism according to claim 1 wherein said second case element further includes a channel and a curved trough, said cable locking structure adjacent to said channel for anchoring said roller, and said curved trough disposed adjacent to said cable locking structure and in communication with one end of said channel for restraining a movable range of said roller.
 7. The cable winding mechanism according to claim 1 wherein a spool is extended from an inner surface of said first case element for securing said spring device and said reel disc thereon, a coupling part is disposed on said spool, and a longitudinal gap is cut through said spool.
 8. The cable winding mechanism according to claim 7 wherein said spring device is a spiral spring having an anchoring end engaged with said longitudinal gap of said spool.
 9. The cable winding mechanism according to claim 7 wherein a thread aperture is formed in the center of said spool and a hole is formed in said second case element corresponding to said thread aperture.
 10. The cable winding mechanism according to claim 9 further comprising a tightness adjusting element, which is penetrated through said hole of said second case element and then screwed in said thread aperture of said spool, for controlling degree of tightness of pulling out or rewinding said cable.
 11. The cable winding mechanism according to claim 7 wherein a retaining opening is formed in the center of said reel disc, and said reel disc is sheathed around said spool through said retaining opening such that said reel disc is fixed on said first case element.
 12. The cable winding mechanism according to claim 11 wherein said friction-reducing member includes a ring-shaped article, which is sheathed around said coupling part of said spool of said first case element and embedded within and contacted with said retaining opening of said reel disc, for reducing the friction between said reel disc and said spool upon rotation of said reel disc.
 13. The cable winding mechanism according to claim 12 wherein said ring-shaped article is a metallic ring.
 14. The cable winding mechanism according to claim 1 wherein said reel disc further includes a top plate and a sidewall substantially perpendicular to said top plate.
 15. The cable winding mechanism according to claim 14 wherein said reel disc further includes: a clamping part disposed on an inner surface of said top plate and in the vicinity of said sidewall such that said cable inside said reel disc is clamped between said clamping part and said sidewall; and a first cable groove and a second cable groove formed at opposite sides of said sidewall, wherein a portion of said cable is supported in said first cable groove and said second cable groove and received within said reel disc, so that said cable extended outside said reel disc is wound around an upper portion and a lower portion of said reel disc to respectively define a first winding cable set and a second winding cable set.
 16. The cable winding mechanism according to claim 15 wherein multiple fastening recesses are formed in said sidewall of said reel disc, and said friction-reducing member includes a partition plate having a hollow portion in the center thereof and multiple protrusion pieces corresponding to said fastening recesses.
 17. The cable winding mechanism according to claim 16 wherein said partition plate is sheathed around and fixed onto said reel disc when said protrusion pieces are engaged with said fastening recesses, so that said first winding cable set is separated from said second winding cable set by said partition plate.
 18. The cable winding mechanism according to claim 15 wherein a notch is formed in said sidewall of said reel disc and arranged between said first cable groove and said second cable groove, and said spring device has a hooking end engaged with said sidewall of said reel disc between said notch and said first cable groove or said second cable groove.
 19. The cable winding mechanism according to claim 14 wherein said friction-reducing member includes at least one salient, which is arranged on said top plate of said reel disc and contacted with said second case element, for reducing the friction between said reel disc and said second case element upon rotation of said reel disc.
 20. The cable winding mechanism according to claim 14 wherein said friction-reducing member includes a least one salient, which is arranged on said a bottom periphery of said sidewall of said reel disc and contacted with said first case element, for reducing the friction between said reel disc and said first case element upon rotation of said reel disc. 